Compressor-controlling apparatus



Nov. 9 1926. 1,606,060

C. E. COX

COMPRESSOR GONTROLLI NG APPARATUS Filed May '7: 1924 2 Sheets-Sheet 1 d2FROM All? KECEIVER Q 2 pmswrae y Clarence E. COX

Nov. 9,1920. 0 1,606,060

c. E. c ox COMPRESSOR CONTROLLING APPARATUS Filed May 7. 1924 2Sheets-Sheet 2" FROM AIR RECE/ v5? C/a/re/vce f. COX y Patented Nov. 9,1926.

UNITED STATES PATENT OFFICE.

r CLARENCE E. COX, FRANKLIN, PENNSYLVANIA, AS SIGNOR TO CHICAGO PNEU-bustion engine/to drive the compressor.

MATIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

COMPRESSOR-CONTROLLING APPARATUS.

Application filed Kay 7,

/Ihis invention relates to apparatus for controlling the operation offluid compressors, pumps andthe'like. It has particular application tothe loading and unloading during starting andestopping periods of aircompressors arranged :tor intermittent op? eration.

. Certain typesof prime movers used to operate compressors arerelatively ineflicient under certain conditions, as when start ing, whenoperating at low speeds, or in a cold condition. The electric motor,which is a particularly desirable type of power unit tor theintermittent operation. of compressors, is characterized by a relativelylow "starting torque, especially the alternating current motor, and byan inability to carry its load until it has attained its operatingspeed. Hence when an electric motor forms the driving element efiicientand positively operating apparatus for maintaining the compressors in anunloaded condition during the starting and stopping periods is arequisite. Such apparatus isdesirable also on installations utilizing aninternal com- Oneof the objects of the invention is to provide simpleand reliable apparatus of the described type which will operate in aneflicient and positive manner during the starting and stopping periods.Another object is to prevent loading of the compressor in case thedriving engine fails to at tainits operating speed. Other objects willbe apparent from the detailed description which follows. p

The invention comprises utilizing a builtup pressure which varies inproportion to and closely approximates in time the variations in speedof the compressor for controlling suitable unloading mechanism on thecompressor. It may take advantage of the fact that the fluid pressuredeveloped by a gear type rotary pump is a function of its speed whensome throttling efl'lect is produced in the discharge line from thepump.

The fluid pressure medium may be from a circulating system associatedwith the compressor as its cooling orits lubricating system, or from asystem specially designed for compressor pontrol. I

order to make clear the nature of the j invention and the manner. of itsoperation, concrete embodiments of the genus constiholding the 1924.Serial N0. 711,558.

tuting the invention are disclosed in the accompanying drawings, inwhich: Fig. 1 is a side elevational view of a compressor partly cut awayto disclose an"'un loading valve and showing the contro1 mechanism forthe latter in section' as on the 1ine-1-e1..ofmEig. 2;

Fig. 2 is an end elevation view of the parts shown in Fig. 1 with thecontrol mechanism disclosed in section substantially on the line 22 ofFig. 1; and

Fig. 3 is a view similar to Fig. 2 showing a modified form of controlmechanism.

The invention is disclosed as applied to a compressor of the air cooledtype and its lubricating system is selected, merely by way ofillustrating the invention and not for limiting it, to provide the fluidpressure medium utilized for the automatic control of the loading andunloading of the compressor. Referring now to the drawings, A is thecompressor having fly wheel B, the same being driven by any suitabletype of prime mover (not shown), such as an electric motor. The fluidcirculating system for lubricating the compressor includes a suitablepump C,'preferably of the gear type, connected to the shaft of thecompressor by a suitable coupling (not shown), the pump having an inletconnection 0 leading to the sump or lubricating reservoir a at thebaseot' the compressor and an outlet connection leading to the splashtrough a and if desired toother parts requiring lubrication, this outletconnection comprising two parts, the' one 0 leading to the casing .4 ofthe control mechanism later 'to be described and the other 0 from casing4; to

splash trough a. i

The compressorhas one or more fluid 0perated unloading valves D of anysuitable or desired type, the one illustrated being the well known plateunloading valve disclosed in U. S. Patent No. 1,27 5,843 issued August13, 1918, to William H. Callan.- The unloading valve D comprisesessentially a cylinder at having a piston d movable therein in onedirection by motive fluid admitted through a pipe connection (2 andarranged to actuate the fingered valve litter d, for plate valve d oflits apertured seat (1, the hfter d. and the piston 0'! being returned toinoperative position by a spring The automatic control mechanism for theunloading valve D comprises the casing 4 having a vertically disposedcylindrical bore 5 therein, within which there is arranged forreciprocatory movement a double headed piston 6, the heads 6 and 6 ofwhich are connected by a stem 7 and form therebetween a chamber 8provided with a constantly open outlet port 9 which communicates withthe fluid connection 0Z extending to unloader valve D. Piston head 6performs the function of a valve in controlling an inlet port 10 fromwhich a pipe 11 leads to the air receiver (not shown) supplied by thecompressor. The piston head 6 likewise functions as a valve incontrolling a VBIItpOIt 12 leading-to atmosphere. The double headedpiston or control member 6 is normally retained in its lowermostposition as shown in Figs. 1 and 2 by a loading spring 13, one end ofwhich spring is received in a socket inthe head 6 .and the other endengages a centering projection on the interior of a range adjusting nut14 in threaded engagement with the casing 4. The double headed piston 6has on its lower end a projectin stem 15 adapted to engage the bracket1% which supports the casing 4 andv closes the I lower end of thecylindrical bore 5. There is thus provided in the lower end of bore 5and below piston head 6 a chamber to which the lubricant issuing frompump C has access through its outlet pipe 0' by means of a horizontalbore 16. Casing 4 above bore 16 has a vertical bore 17 joining bore 16by a reduced opening 18 thereby formin a seat 19 for a check valve inthe form of a all 20 urged toward its seat by a spring 21,'the tensionof which may be adjusted by a screw 22 threaded into the upper end ofbore 17. A washer 23 and lock nut 24 hold screw 22 in adjusted position-A vent 18' leads past check valve 20 into bore 17 to which the sec- 0ndpart or section 0 of the outlet pipe from disclosed through pipe doutlet 9, chamber 80f the control device, inlet 10 and pipe 11 whichconnects with the air receiver. Thus the compressor is entirelyunloaded. When the prime mover for the compressor isstarted,

pump 0 immediately begins to force oil from d the sump a into casing 4,the oil discharged by the pump entering bore 16 and the chamber belowthe piston head 6 of the control device and being vented through opening18 to bore 17 and thence through pipe 0 to the splash trough a' With,the development of pressure spr g 21 of heck valve threaded engagementtherewith.

20 yields, being of much less resistance than of the spring 13 isovercome whereupon the double ended piston control member 6 movesupwardly, piston head 6 closing air inlet 10 and piston head 6uncovering vent 12 whereupon the motive fluid which has previously actedon piston 03 of the unloader valve D is exhausted, and plate valve ol isthereupon released to function as an inlet valve and the compressor isloaded. In the upward movement of member 6 the end of stem ,15

is exposed, thus increasing the area subjected to the pressure of thelubricating system so that member 6 moves quickly and positively to itsupper position. Thus control member 6 through its stem 15 has adifferential area subjected to the pressure in the lubricant.

When the pressure in the lubricating system falls through reduction incompressor speed, spring 13 restores control member 6 to its originalposition so that chamber 8 is again closed to atmosphere and opened tomotive fluid from pipe 11 and unloading valve D is placed in operation.

In Fig. 3 a modified form of controldevice is shown, the principle ofoperation, howevenbeing substantially the same. The control devicecomprises a casing 25 having a large horizontal bore 26. and a. smallervertical bore 27 provided witha reduced extension 28 joining bore 26 andforming a seat for a check valve 29 which has a small vent 28. Outletpipe 0 connects with reduced bore 28 below checkv valve 29 and pipe 0with bore 27 above the check valve. Within bore 26 isa piston 30 backedby a loading spring 31 and a vented range adjusting nut 32, these partsclosing one end of bore26. The other. end of bore 26 is closed bya'casing 33 in Casing 33 has a horizontal bore 34 at its outer end witha reduced extension 35 coaxial with bore 26 and communicating therewith.Within chamber 34 is a-valve 36- cooperating with a seat at the entranceto bore 35 and having a reduced stem 37 provided with a cylindrical end38 tit-ting bore 35 and arranged to control a vent port 39 and to engagea projection 40 on piston 30 which projection has a bevelled edge whichseats in a similarlyt bevelled socket 41 in casing 33. A spring Ill (1leading tounloader valve D. Projection 40 on piston 30'ope rates to makethe latter a 'difi'erential piston in the same manner that stem acts inthe modification shown in Figs. 1 and 2.

v The operation of the modification shown in Fig. 3 will be apparentfrom the draw-' 'ing as a valve uncovers vent 39 to relieve theunloading valve D and to permit the latter to function as an inletvalve. When the pressure in the lubricating system falls,

the Fi 7 mm the above it will be apparent that both forms of theinvention herein disclosed provide simple and positively operated meansfor maintaining a compressor in unloaded condition when the same isoperated the check valve and the amount of flow thereby adapt thecompressor to use with prime movers having widely varying powercharacteristics. p

Having now described my invention and the manner of its use, whatIclaimand desire to secure by Letters Patent is:-

1. In combination, a compressor having a lubricant circulating systemoperating in proportion to the speed of the compressor,

including a pump and a chamber into which the pump discharges. a valveyieldably opposing the passage of fluid from said chamber, a restrictedby-pass around said valve to permit a circulation of said fluid at alltimes a fluid pressure operated unloader for said parts return to theposition shown in compressor, and means responsive to built up pressureof said fluid in said chamber for controlling the admission of motivefluid to said, unloader to actuate the same.

2. In combination, a compressor having a liquid circulating systemoperating in proportion to the speed of the compressor including a pumpand a chamber into which the pump discharges, a valve-yieldahly opposingthe passage of liquid from said chamber, means for varying theresistance of said valve to the passage of said liquid, a'restrictedby-pass around said valve to permit the circulation of said liquid atall times, an unloader for said compressor, and means responsive "to thepressure of said liquid in said chamber for controlling said unloader.

liquid circulating system operating in pro- .portion to the speed of thecompressor including apump and a chamber into'which the pump discharges,a valve for op osing the passage of liquid from said cham er, a springarranged to press said valve to its seat, means for adjusting thetension of said spring, an uirloader'for said compressor, and meansresponsive 'to the pressure of said liquid in said chamber forcontrolling said unloader. I

(i. .A controlling device for compressors having fluid operatedunloading means and lubricant circulating systems comprising a casinghaving a chamber forming a part of the lubricant circulating system, avalve yieldingly controlling the outlet of said chamber to cause thelubricant to build up pressure in said chamber, means for adjustablypredetermining the yielding tension on said valve, a restricted by-passaround said valve to insure circulation in said lubricant system at alltimes, a piston movable in 3. In combination, a compressor having aresponse to the built up pressure in said chamber, adjustable meansforyieldingly opposing movement of said piston, and valve means carried bysaid 'piston and arranged to connect the unloadingmeans of thecompressor either to a source of fluid pressure or to exhaustdependentupon the position of said piston.

Signed b me at -Franklin,'-Penna., this 30th day 0 April, 1924.

p CLARENCE E. COX.

